The monoammonium salt of 5,5′-bis-1H-tetrazole (BTA-NH3) has been found to be an excellent fuel for use in gas generants, in airbag inflators within vehicle occupant protection systems, for example. It has been found that the particle size and morphology of this fuel constituent nevertheless affects the performance of formulations that use it. It is believed that needle-like crystals of BTA-NH3 tend to bend and flex when exposed to a thermal gradient cycle spanning −40 C to 107 C. This effect creates aggressive ballistic results for propellant formulations that contain larger crystalline BTA-NH3 particles.
Smaller and amorphous BTA-NH3 particles apparently mitigate the detrimental effects of the bending and flexing of the larger needle-like structures. Accordingly, the size and shape of the BTA-NH3 particle has been found to be determinative of the stability of associated gas generant compositions with regard to temperature cycling or heat aging criteria. Furthermore, the improved bulk density provides advantageous packaging and storage requirements for BTA-NH3 when processed to produce particles having a desirable shape and size. When synthesized to the desired shape and size range, grinding to the desired size and shape is eliminated as a time critical step in the manufacturing process of BTA-NH3. Eliminating the grinding step also mitigates variability in combustion performance due to inconsistencies in the grinding process and therefore, inconsistencies in the average size of the BTA-1NH3.